The determination of the role of radiant energy in the pathogenesis of pigmentary degenerations of the macula. The determination of the effectiveness of light filters in preventing or arresting pigmentary degenerations of the macula. What etiologic diagnoses can be established with certainty in a series of patients with apparently unexplained optic neuropathy? How valid are the more common diagnostic labels applied to certain groups of patients with optic neuropathy? What genetic, epidemiological and clinical features characterize those examples of optic neuropathy whose origin remains unexplained even after intensive multidisciplinary investigations? What are the natural histories of this population of patients? What are the influences of intraocular and blood pressure on the progression of optic neuropathy not necessarily of vascular or glaucomatous origin? What is the effect of hyperthermia and exercise on the visual function of these patients?